In many cases, it is difficult for elderly people having muscle strength decline or physically handicapped people having lost muscle strength to perform an action or operation that can easily be performed by a healthy person. For this reason, development of various power assist devices is now in progress in order to assist or execute action of these people by substituting for them.
Among these power assist devices, there is a wearable action-assist device (which is also called action-assist device) which is put on a user (which is also called wearer), for example. Typically, the power-assist device of this kind includes a myoelectricity sensor (biosignal detection unit) which detects a myoelectricity signal accompanied with a wearer's muscular line activity, a joint angle detecting unit which detects an angular displacement of each joint of the wearer, a drive source, such as a drive motor, which supplies torque as an assisting force for the wearer, and a control unit which controls the drive source. And the power-assist device of this kind is under development. For example, see the non-patent document 1 mentioned below.
In this power-assist device, the control unit controls the drive motor suitably based on the detection result by the myoelectricity sensor and the detection result by the joint angle detecting unit. This will enable the torque conforming to the wearer's intention and suitable for the current action to be given to the wearer concerned. It is expected that this power-assist device is realized.
[Non-patent Document 1]
    “Development of Power Assistive Leg for Walking Aid using EMG and Linux” by Takao Nakai, Suwoong Lee, Hiroaki Kawamoto and Yoshiyuki Sankai, Second Asian Symposium on Industrial Automation and Robotics, BITECH, Bangkok, Thailand, May 17-18, 2001